Loudspeakers, including headphones, have been widely used in daily life. Headphones are a pair of small loudspeaker drivers worn on or around the head over a user's ears, which convert an electrical signal to a corresponding sound.
Wired headphones, however, constrain the users' movement because of the wires (cords), and are particularly inconvenient during exercise. Conventional wireless headphones no longer need the wires between the headphones and the audio sources, but still require the wires between the left and right headphones.
True wireless stereo (TWS) headphones (also known as untethered headphones) is a type of wireless headphones that remove the wires between the left and right headphones. However, because of the limitations of the wireless communication technologies, error in wireless transmission of data (e.g., data packets) happens. When the audio information received include errors (i.e., not successfully received), audio sources will re-transmit the audio information for predetermined times or till it is correctly received. Upon receiving the data, conventional wireless headphones make hard decision decoding/demodulation on the data (e.g., take on a fixed set of possible values). This would lose information encoded in the transmitted data and reduce the accuracy of the demodulation. As a result, more times of re-transmission would be required and thus waste resources and time.